Method for contactless evaluation of characteristics of semiconductor wafers and devices
US4949034A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Mar 13, 1989 |
| Grant date | Aug 14, 1990 |
| Priority date | — |
| Expiry date | Mar 13, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R31/308
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
This invention discloses a method for contactless evaluation of characteristics of semiconductor wafers and devices. The method includes the steps of (a) continuously irradiating focused microwaves on a surface of a semiconductor specimen; (b) continuously receiving reflected microwaves reflected from said surface; (c) irradiating a focused laser beam pulse on the specimen, energy of the pulse being in excess of the band-gap energy of the semiconductor material; (d) measuring lifetime .tau..sub.m from the time-history of the characteristics of the reflected microwaves; and (e) calculating the surface recombination velocity S and bulk lifetime .tau..sub.b. The focused microwaves and focused laser beam can improve the resolution during measurement. Furthermore, the method includes the steps of: (a) continuously irradiating microwaves on a surface of a semiconductor specimen; (b) continuously receiving reflected microwaves reflected from said surface; (c) irradiating a laser beam pulse on the specimen, energy of the pulse being in excess of the band-gap energy of the semiconductor material; and (d) changing the characteristic of the reflected microwaves to an electrical signal, for ob…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.